Optimization of the x-ray spectrum and radiation symmetry in the hohlraum

The ultimate goal of laser-driven hohlraum is to create a radiation environment that ablatively implodes a capsule to ignition and burn. To obtain high fusion yield with minimum laser energy, the hohlraum drive must meet both the limited non-Planckian emission (M-band) and excellent uniformity. On the series of Shenguang laser facilities, several experiments have been done to characterize the x-ray spectrum and radiation symmetry of the laser-heated hohlraum. By optimizing the hohlraum structures and materials, the hohlraum performance was improved in flux intensity, symmetry and spectrum.